Find the number of triangles in the given figure.
A.
10
B.
19
C.
21
D.
23
Correct answer is C
The figure may be labelled as shown.
The simplest triangles are ABI, BIC, AIJ, CIJ, AHJ, CDJ, JHG, JDE, GJF and EJF i.e. 10 in number.
The triangles composed of two components each are ABC, BCJ, ACJ, BAJ, AJG, CJE and GJE i.e. 7 in number.
The triangles composed of four components each are ACG, ACE, CGE and AGE i.e. 4 in number.
Total number of triangles in the figure =10+ 7 + 4 = 21.
